Clamp.



A. McMURlRIE.

CLAMP.

APPLICATION FILED NOV; 27,1911- RENEWED NOV. 2], H6- 1 230,7 12 PatentedJ une 19, 1917.

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ADNAH MOMUBTBIE, OF NEW YORK, N. Y., ASSIGNOR T0 THOMAS & BETTS COMPANY,OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

CLAMP.

Specification of Letters Patent.

Patented June 19, 1917.

Application filed ll'ovember 27, 1911, Serial No. 662,715. RenewedNovember 21, 1916. Serial No. 132,715.

To all whom it may concern:

Be it known that I, ADNAH McMUR'rRrE, of New York, N. Y., have inventedcertain Improvements in Clamps, of which the following description, inconnection with the accompanying drawings, is a specification, likereference characters on the drawings designating like parts.

This invention relates to clamping devices and is of particular utilitywhen embodied in a clamp for electrical conduit, although I contemplatethe utilization of my improvements in any field for which they areadapted by their nature.

An important object of my invention is to provide a grounding clampwhich term I use without technical limitation as a brief and convenientdesignation for a device for efieeting mechanical and electricalconnection between such an electrical conduit memher as a ceiling boxand a gas pipe projecting through the conduit box to receive achandelier, it being desirable to insure a path of good conductivity forany electrical current which may accidentally flow from the chandelierto the gas pipe, so that destrnctive arcing will be avoided.

, Another object of my invention is to provide an attachment of theclass described which can be used upon various sizes of pipe withoutrequiring special adjustments prelry to emplacement, the adjustmentbeing effected automatically by the act of setting the fastening devicesemployed to secure the attachment in place.

Other objects of notable importance include the construction of thedevice in a plurality of symmetrical parts of identical construction, sothat but one form of pattern will be required in their manufacture, andany two of the members may be secured together in opposed relation,without pre liminary selection, to embrace between them the article towhich attachment is to be effected, as for example the gas pipe to whichreference has already been made.

Another object consists in the construction of the attachment in such amanner that it does not require an expensive preparatory threadingoperation to fit it for emplacement, but can be secured by ordinarymachine screws or by stove bolts and nuts passed into the usual holesfound in the bases of outlet boxes, these holes being sometimes threadedand sometimes plain. My improved attachment constitutes a universalfitting for these conduit members.

Another object of my invention is to provide a convenient method ofattaching a ground wire to a pipe or conduit where no outlet box isused. In such a-"case the ground wire may either be coiled under thehead of the bolt, or secured to a lug held under the head of the bolt.The lugs on one of the component parts of themlamp may have threadedholes instead of slots, and then ordinary machine screws may be used inplace of bolts.

This lateral movement of the segments relatively to each other, has theeffect of scraping their contacting surfaces to cause a good electricalconnection, and the co-axial play gives a scraping contact of the seatportions of the segment with the pipe embraced therebetween, while thethreaded engagement of the bolts and the scraping action of their headsupon the segment lugs and the base respectively completes the electricalunion between the pipe, clamp and box.

The various features of my invention will I be illustrated and describedfully in the accompanying drawings and specification and set forth inthe claims.

In the'drawings,

Figure 1 is a view, in vertical section, of an installation comprisingan outlet box, a gas pipe and a grounding clamp in the construction ofwhich my invention has been embodied.

Fig. 2 is a view in perspective of the component members of the clamp,shown separately, but in position for assemblage; and

Fig. 3 shows the clamping members in assembled relation separately fromthe box.

In the embodiment of my invention selected for illustration anddescription to permit ready and complete understanding of myimprovements, the parts designated by the reference numeral 1 are themembers of my improved clamp, which are shown, by way of example, asconstituting the component parts of a grounding clamp to effect physicaland electrical connection between a gas pipe 2 and the box 4 shown inFig. 1, which may be considered to represent an electrical conduitoutlet box especially adapted for ceiling and other wall installations,such boxes usually having apertures c to admit ehctrical conduit, withknockgas pipe 2, it being usual also to have holes 12 in the base of thebox, to receive attaching screws or bolts 14, with nuts 16, if desired,the holes 12 being threaded in some instances, and not threaded inothers.

The clamping members 1 may be of any material and construction suitableto carry my invention into efiect, and as one suitable form ofconstruction I have shown them as segments of cast iron and comprisingeach a concave seatportion 18 and attaching lugs 20, which may, andpreferably will, be located at each end of the segments respectively.

In. accordance with my invention, these segments are provided with meansto cause lateral approach of one toward the other upon relative movementthereof along the axis of the article to which attachment is to beefiected,vand such meansmay be of any suitable type.

The construction illustrated herein, by

,Waypf example, to efi'ect this clamping movement, comprises inclinedcam-surfaces 22, of any suitable number, there being two of thesesurfaces upon each of the segmental members shown, one on each of theterminal lugs 20, the cam-surfaces being inclined across the axis of theclamp.

By this arrangement of the inclines 22, and when, as I prefer, thesegmental members 1 are of identical construction, so as to besymmetrical when assembled, as shown in Fig. 3, embracing the pipe 2, nospecial preliminary operation is required to prepare the pipe or boxwall to receive the clamping members, the latter being self-contained,the lugs 20 registering,- so that the inclines 22 enter intocofiperative engagement by virtue of the act of assembly.

Any suitable means may be provided for operation of thev clampingmembers into clamping relation with the article to which attachment isto be effected, and as one convenient form of operating device I haveshown the lugs 20 as slotted at 24 to receive screws 14 with heads 26,the heads being engaged with the lugs of one of the members, when thescrews are driven home, to cramp the members 1 together axially, withthe result that they are also cramped together laterally, the inclinedcam-surfaces 22 sliding on each other as already described.

I prefer to provide each of the lugs with the elongated slots 24illustrated, thus giving opportunity for a wide play of the clampingmember, to accommodate it to articles varying considerably in width, asfor example to a half inch size of gas pipe and to a three eighths sizeas well, and by use of the bolts 14 screwed intothe box wall 15 incenseat 12, with or without the nuts 16, I am enabled to avoid the necessityof providing. threaded holes in the lugs 20.

In operation of my improved clamp, using by way of example theinstallation illustrated in Fig. 1, the box 4 and pipe 2 having beenfitted together, the segmental members 1 are assembled, embracing thepipe 2,

with the slotted lugs 20 registering and the inclined surfaces 22 inengagement, and the bolts 14 are then driven home forcing the cams 22together and cramping the concave seat portions into tight engagementwith the pipe 1, thus uniting the pipe 1 and box 4 physically andelectrically.

It is to be observed that by the double relative movement of theclamping members 1, there is induced a scraping contact between alltheir contacting surfaces, and this insures good electrical unionbetween members 1 through came 22, and between screw heads 26 and lugs20; also between screws 14 and box 4, and between clamping seat portion7 and pipe 2. To render the last named physical and electrical (mntactstill more perfect, I may provide projections, such as the ribs 27, onseat portions 7, and these ribs will bite into the periphery of pipe 1,as they are moved co-am'ally therealong by action of cams 22.

Having described my invention thus fully and suitable means by which thesame may be put in practice, I wish it to be understood that I do notlimit myself to the specific materials and forms of constructionselected for illustration and description by way of example, nor ingeneral do 1 limit myself otherwise than as set forth in the claims readin connection with this specification.

What I claim and desire to secure by Let.

said slots being extended to permit approach of said segments fromopposite sides into operative relation with said pipe, and said lugsoverlapping when in said operative relation and having their proximatesurfaces inclined across the plane of juncture, serving as cooperating.cam-surfaces to cramp said members together toward the am's of saidpipe, said cooperative sliding engagement serving also to promoteelectrical union of said members with each other, and the abrasiveaction of said projections serv ing to promote electrical union of saidmembers with the periphery of said pipe, and the action of saidoperating bolt members serving by abrasion of their heads and said lugs,to complete the electrical grounding of said conduit member through saidbolts and segments to said pipe.

2 A grounding device of the class described; comprismg a segmentalmember having a medial concave seat portion and terminal slotted lugs oneach side thereof with cam faces inclined across the axis of 3. Agrounding device of the class described; said device comprising aplurality of symmetrical, segmental members having respectively medialconcave seat portions and slotted terminal lugs on each side oi saidrespective seat portions, with cam faces inclined across the axis ofsaid seat, said members being assembled with said lugs overlapping andsaid cam faces in engagement; substantially as described" Signed at NewYork in the count and State of New York this 15th day of ovember, 1911.

ADNAH McMURTRIE. Witnesses Wm. H. McConmcx, ALEX. C. Pnounrrr.

